A light-emitting unit comprising a lighting unit and a projection unit is known.
The “UKW-Radio mit Projektionsuhr” [VHF radio with projection clock] by LUNARTEC (http://www.pearl.de/a-PE6822-1606.shtml) discloses a light-emitting unit comprising a luminaire, a projector and an integrated VHF radio. The luminaire performs the function of spreading a relaxing and pleasant light, and the projector projects a time of day in the direction of the ceiling of a room. An LED lamp acts as light source.
One disadvantage with this solution is its lack of flexibility in use. For example, the light is emitted diffusely substantially uniformly in the direction of the complete half space above the standing area of the radio. It is comparatively weak, cannot be focused and its luminous intensity is not variable. Thus, the luminaire of the light-emitting unit is not suitable for lighting tasks with more stringent requirements in respect of the light quality. An application area of the projector is likewise restricted. Thus, for example, the projection direction of the time of day is fixed or non-adjustable and the content of the projection or the information content of the projection is exclusively restricted to the time of day.
A “Space Projector” by Mathmos (http://www.mathmos.de/space-projector-light-9466-0.html) features a light-emitting unit comprising a luminaire and a comparatively more versatile projector, wherein the luminaire and the projector have a common light source. The luminaire propagates an ambient light over a diffuse-transparent housing part, and the projector projects an image of a transparent graphics or gobo disk with or without an upstream color filter in a spatial region slightly above a horizontal. The graphics or gobo disk or the color filter can be changed manually and a sharpness of the projection is manually adjustable.
One disadvantage with this solution furthermore consists in that the projection direction is fixed and is only variable via a change in the alignment of the space projector on its standing area. The projection is restricted to artistic content. The luminous efficiency is low and is not suitable for task lighting, for example for reading.
The two light-emitting units from the prior art have the common feature that they are inflexible in terms of their application and are very limited.